This application is a national stage of PCT International Application No. PCT/EP2009/000503, filed Jan. 27, 2009, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2008 017 950.7, filed Apr. 9, 2008, the entire disclosure of which is herein expressly incorporated by reference.
The invention relates to a method for influencing the transverse dynamics of a vehicle.
German patent document DE 102 36 331 A1 discloses a generic method for operating a vehicle steering system which can generate a steering angle by means of an actuator, for compensating a disturbance yaw moment independently of a steering angle preset by the driver of the vehicle with the steering wheel. If the actuator fails, the following steps are carried out after initiating a steering angle that compensates a disturbance yaw moment (which remains with a failed actuator): an actuator yaw moment generated by the actuator is calculated, and a compensating counter-yaw moment is slowly built up by automatic application of a longitudinal wheel force, in order to enable the driver to counteract a steering angle to this yaw moment. Subsequently, the counter-yaw moment is reduced slowly in order to enable the driver to balance the yaw moment occurring due to the steering angle still present by means of a steering angle generated by the steering wheel.
German patent document DE 10 2004 017 638 A1 discloses a method and apparatus for a vehicle for determining at least one side wind value. The latter is estimated by means of a transverse acceleration value and a yaw rate value based on a vehicle model. The transverse acceleration value and of the yaw rate value can be detected, for example, by specially formed transverse acceleration sensors or yaw rate sensors. The vehicle model can for example be a linearized transverse dynamics one-track model.
Finally, a method for side wind stabilization of a motor vehicle is known from German patent document DE 10 2004 057 928 A1, in which a side wind magnitude is estimated, which reflects a side wind influence exerted on the vehicle. For compensating the effect of the side wind on the vehicle, the transverse dynamics of the vehicle are adjusted dependent on the estimated side wind magnitude. For this purpose, wheel contact forces acting on the wheels thereof are modified, namely in such a manner that the side wind influence exerted on the vehicle can be compensated.
One object of the present invention is to provide an alternative or improved method of the generic type, which offers particularly good compensation of side wind influences acting on a vehicle.
This and other objects and advantages are achieved by the invention which is based on the general idea to at least partially compensate the dynamic and the stationary part of a transverse dynamics disturbance variable of a transverse disturbance acting on a vehicle, in particular a side wind. The method according to the invention uses two vehicle systems for this, with the help of which counter-yaw moments can be generated for the at least partial compensation of the transverse dynamics disturbance variable. The method according to the invention thereby uses the following method steps in principle:
The dynamic part of the transverse dynamics disturbance variable is first detected by a disturbance variable determination device, and a first counter-yaw moment is then effected with the help of a first vehicle system for the at least partial compensation of the dynamic transverse dynamics disturbance variable.
Subsequently, the first counter-yaw moment is reduced or removed after the at least partial compensation. It is then checked, with the help of the disturbance variable determination device, whether a stationary transverse dynamics disturbance value is present as a stationary part of the transverse dynamics disturbance variable, and if so, a second counter-yaw moment is generated with the help of a second vehicle system for the at least partial compensation of the stationary transverse dynamics disturbance variable. It is thus possible by means of the method according to the invention to support the driver with the at least partial compensation of the dynamic part and with the at least partial compensation of the stationary part of the transverse dynamics disturbance variable—for example of a disturbance yaw moment.
The dynamic transverse dynamics disturbance variable is effectively compensated at least partially with a low reaction time by a first vehicle system (for example, a wheel brake intervention), while the at least partial compensating of the stationary transverse dynamics disturbance variable takes place by a second vehicle system (for example, a steering system). The generation of the second counter-yaw moment can thereby take place by a second vehicle system, whose comfort is larger for the driver when generating the second counter-yaw moment than the comfort when generating the first counter-yaw moment by the first vehicle system, as the second counter-yaw moment is often needed for a considerably longer time compared to the first counter-yaw moment.
By means of the method according to the invention, it is possible to choose the second vehicle system in such a manner that the comfort requirements are fulfilled. However, in order to be able to react to the dynamic part in a sufficiently fast and effective manner with a high dynamics, the dynamic transverse dynamics disturbance variable is counteracted by the first counter-yaw moment, which is generated by the first vehicle system and which has to fulfill distinctly lower comfort requirements and which can be optimized with regard to the build-up dynamics of the first counter-yaw moment with a detected dynamic transverse dynamics disturbance variable.
The first counter-yaw moment is advantageously generated at one of the wheels by a wheel brake intervention for the at least partial compensation of the dynamic transverse dynamics disturbance variable. A first counter-yaw moment can be built up by the brake system or a wheel brake intervention in a particularly dynamic and fast manner.
In an advantageous further development of the invention, the second counter-yaw moment is used for the at least partial compensation of the stationary transverse dynamics disturbance variable with the help of a second vehicle system, whose activation is influence-free with regard to the longitudinal vehicle speed, whereby a sufficiently high driving comfort can be ensured during the generation of the second counter-yaw moment.
In particular, the steering system can be used as second vehicle system, wherein a steering moment is generated in particular with the help of a steering moment adjuster, which supports the driver when generating the second counter-yaw moment. E.g. the driver does not continuously have to apply a hand moment to the steering wheel but is supported or completely relieved by the steering moment adjuster. The steering moment adjuster can be designed in a manner that can be accessed very easily as an electric motor and thus be operated electrically. The steering moment applied to the steering system, in particular a steering column, by the steering moment adjuster can be perceived by the driver at the steering wheel.
The driver can thereby first be supported by the steering torque adjusted with the at least partial compensation of the stationary transverse dynamics disturbance variable, while the compensation of the dynamic transverse dynamics disturbance variable takes place only via the wheel brake intervention, so that a sufficiently high dynamics and simultaneously a high driving comfort is achieved for generating the second counter-yaw moment.
It is advantageous if the disturbance variable determination device detects the dynamic transverse dynamics disturbance variable in that a side wind magnitude is estimated by means of a transverse acceleration value and/or a yaw rate value on the basis of a vehicle model and in particular a disturbance observer. A simple and safe detection of side wind influences is possible thereby. It is additionally advantageous if the stationary transverse dynamics disturbance variable is detected, in which, after the detection or the at least partial compensation of the dynamic transverse dynamics disturbance variable, a steering angle and/or a steering wheel angle and/or a hand moment applied to the steering wheel and/or a variable correlating with the mentioned variables is evaluated. In this manner, the stationary transverse dynamics disturbance variable can be determined in a simple and safe manner. A transverse dynamics variable such as a transverse acceleration and/or a yaw speed can for example be used as correlating variable.
The above-mentioned characteristics which will be explained in detail hereinafter can be used not only in the respectively given combination but also in other combinations or on their own without exceeding the scope of the present invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.